Phosphorescence-Sensitizing Fluorescence Material Electron-Transfer Barrier

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Solution Overview

Problem

Conventional phosphorescent-sensitized fluorescent systems face challenges in achieving high efficiency due to exciton quenching caused by triplet-triplet Dexter energy transfer between the sensitizer and acceptor groups, leading to reduced radiative efficiency in organic light-emitting devices (OLEDs).

Innovation Solution

Incorporating an electron-transfer barrier with a maximum length of less than 10 nm between the sensitizer and acceptor groups to suppress triplet-triplet energy transfer, while maintaining Forster energy transfer, thereby preventing exciton quenching and enhancing energy transfer efficiency in OLEDs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the sensitizer and acceptor groups are placed in close proximity to enhance energy transfer, then the energy transfer efficiency is improved, but triplet-triplet Dexter energy transfer causes exciton quenching and reduces radiative efficiency

Engineering Contradiction:

Improveenergy transfer efficiencyVSAvoidexciton quenching

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent introduces an electron-transfer barrier as an intermediary component positioned between the sensitizer and acceptor groups. This barrier has specific energy levels that prevent triplet-triplet Dexter energy transfer while allowing Forster energy transfer to proceed, thus mediating the energy transfer process to eliminate exciton quenching while maintaining efficiency

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies local quality by creating a distinct region with different electronic properties (the electron-transfer barrier) within the molecular system. This barrier has tailored energy levels and electron transfer characteristics that differ from the surrounding sensitizer and acceptor groups, allowing selective suppression of harmful interactions while preserving beneficial ones

Inventive Principle:

Principle #3Local quality

2Reliability

If an electron-transfer barrier is introduced to suppress triplet-triplet energy transfer, then radiative efficiency is improved, but the device structure becomes more complex

Engineering Contradiction:

Improveradiative efficiencyVSAvoidmolecular structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the electron-transfer barrier functionality into the molecular structure by covalently linking it between the sensitizer and acceptor groups. This integration approach combines multiple functions (energy transfer mediation, exciton quenching prevention) into a single molecular component, reducing the need for separate structural elements

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent employs composite material principles by creating a hybrid molecular structure that combines organic sensitizer groups, acceptor groups, and electron-transfer barrier segments. This composite molecular architecture leverages the complementary properties of each component to achieve enhanced radiative efficiency while managing structural complexity

Inventive Principle:

Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The electron-transfer barrier effectively reduces non-radiative quenching, leading to improved radiative efficiency and enhanced performance in phosphorescence-sensitized fluorescence systems by isolating the sensitizer and acceptor groups, thus promoting energy transfer and reducing exciton loss.

Implementation Method 1

triplet-singlet Forster resonant energy transfer to convert energy from an exciton formation source to an energy state with longer wavelength emission

Methodology Applied

Scientific EffectForster energy transfer:

Implementation Method 2

triplet-triplet energy transfer between the sensitizer and acceptor groups

Methodology Applied

Scientific EffectDexter energy transfer:

Implementation Method 3

phosphorescent-sensitized fluorescent systems

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentUS9653691B2Phosphorescence-sensitizing fluorescence material system

Publication Date: 2017.05.16 UNIVERSAL DISPLAY CORP

AI summary

Novel molecules are provided that include a sensitizer group, an acceptor group, and an electron-transfer barrier that suppresses triplet-triplet energy transfer between the sensitizer group and the acceptor group. Organic light emitting devices (OLEDs) that include a layer including these novel molecules are also provided. These devices may be used to provide highly efficient OLEDs with longer operational lifetime.